#pragma once

#include <iostream>
#include <string>

class BigInt {
public:
    // Step1: 默认构造初始化内部状态为 0
    BigInt() {}

    // Step1: 输出运算符直接打印常量 "0"
    friend std::ostream& operator<<(std::ostream& os, const BigInt&) {
        os << "0";
        return os;
    }
};